Without limiting the scope of the invention, its background is described in connection with spinal joint prosthesis and methods and devices for enhancing spinal stability and alignment. A variety of artificial prosthesis are used to replace chronically injured or ruptured intervertebral discs and range from plate inserts, ball and socket joints, gel filled enclosures, spring-biased plates, plate and joint combinations and others.
For example, U.S. Patent Publication No. 20080262550 discloses methods for stabilizing upper and lower spinal vertebrae having a disc situated between the upper and lower vertebrae are described. First and second fasteners are inserted into the upper vertebra. Third and fourth fasteners are inserted into the lower vertebra. At least two of the first, second, third, and fourth fasteners are connected with an elongate element. In an alternative embodiment, at least three of the first, second, third, and fourth fasteners are connected with the elongate element. The elongate element may be an elastic connector or a cable. The elongate element may also have first and second ends that are connected by a crimp.
Another example is taught in U.S. Pat. No. 6,770,096 which relates to an interbody spinal stabilization method and an interbody spinal stabilization cage. The cage has a parallelepipedic shape and comprises a central hollow space intended to be filled with bone fragments. The cage also comprises anchoring device(s) having an overall S shape and opening onto lateral faces connecting with adjacent vertebrae, actuated by at least one actuation device opening into a front face. The anchoring device(s) each have at least one main cutting edge.
Another example of a spinal cage is taught in U.S. Patent Publication No. 20090054991, which discloses a spinal cage system for inserting a spinal cage assembly into a spine to separate and support adjacent spinal vertebrae, that includes a first cage member; a second cage member; and an articulating mechanism adapted to connect the first cage member to the second cage member and to permit the first and second cage members to move relate to each other. An insertion instrument is adapted to capture the spinal cage assembly for insertion of the spinal cage assembly into a spine and to rotate the first and second cage members relative to each other to achieve a desired orientation in the spine.
Finally, U.S. Pat. No. 7,824,445 discloses an improved artificial spinal implant system for replacing a disc or vertebral body that provides adjustability in height, and provides support and stability of the spine with proper lordosis or kyphosis, osseous-integration of the implant, and motion preservation (if desired) of the adjacent vertebrae while preserving the space. Motion preservation in the Biro invention is achieved with compressible and/or tiltable artificial discs.